Marketing firms have sold this data to retailers and credit-card companies for years, and health plans have recently discovered they can use it to augment claims data.

WSJ: How the Insurer Knows You Just Stocked Up on Ice Cream and Beer

"This isn't going to be an excuse to eat French fries all day and watch TV but is a way to augment your healthy lifestyle and give you the ultimate benefits of perfect health which your body is capable of, " Professor Sinclair told the BBC.

BBC: Stop, rewind: the scientists slowing the ageing process